Lubricating greases containing salts of



United States Patent Ofi ice 3,125,523 LUBRICATING GREASES CONTAININGSALTS OF DEBURG ACIDS WITH AMINES William R. Siegart, Wappingers Falls,and Norman R. Odell and Fred C. Toettcher, Fishkill, N.Y., and Edward L.Kay, Akron, Ohio, assignors to Texaco Inc., New York, N .Y., acorporation of Delaware No Drawing. Filed Jan. 17, 1961, Ser. No. 83,1786 Claims. (Cl. 252--33.6)

This invention relates to lubricating greases and to a novel class ofadditives therefor. More particularly, it relates to lubricating greasescontaining amine salts of tetra-covalent diboro acids.

Amine salts of tetra-covalent diboro acids are disclosed and claimed asnovel compounds in copending-application Serial No. 83,176, of Edwin C.Knowles and Edward L. Kay, filed of even date herewith. We have found,in accordance with the present invention, that these compounds areemployed with particular advantage in lubricating greases thickened withhydroxy fatty acid soaps, wherein they impart greatly increased droppingpoints and other advantages, differently from their effect inlubricating greases generally, including greases thickened withconventional fatty acid soaps.

The amine salts of tetra-covalent diboro acids employed in accordancewith the present invention are compounds represented by the followinggeneral formula:

wherein R is a hydrocarbyl radical containing 1 to 24 carbon atoms, R isan aliphatic hydrocarbyl or hydroxy substituted aliphatic hydrocarbylradical containing one or more carbon atoms and preferably at least 8 toabout 30 carbon atoms and R" and R are hydrogen, aliphatic hydrocarbylor hydroxy substituted aliphatic hydrocarbyl radicals containing 1 to 24carbon atoms. The preferred compounds are those wherein R is a tertiaryaliphatic hydrocarbyl group containing from 8 to 24 carbon atoms and R"and R are hydrogen.

The term hydrocarbyl radical when used herein denotes a monovalenthydrocarbon radical.

Suitable compounds of the above class include the following: octylaminesalt of pentamethoxy diboro acid, dodecylamine salt of penta-n-propoxydiboro acid, dodecylamine salt of penta-secondary-butoxy diboro acid,tertiary dodecylamine salt of penta-benzyloxy diboro acid, tertiarydodecylamine salt of penta(nonylphenoxy) diboro acid, hexyldecylaminesalt of tri-n-propoxy-di-isopropoxy-diboro acid, dodecylamine salt oftri-n-propoxydi-pentabutoxy diboro acid, octylamine salt oftri-n-propoxy-di-beta-chloro-ethoxy diboro acid and tertiaryhexyldecylamine salt of tri-(nonylphenoxy)-n-di-propoxy diboro acid.

Formation of the amine salts of tetra-covalent diboro acids takes placereadily over a wide range of conditions. The tetra-covalent diboro acidsmay be prepared by merely mixing together a diborate ester and alcoholin equimolecular proportions at room temperature in the presence orabsence of a solvent, and then reacting the product with the theoreticalamount of amine, on the basis of one amine group to each molecule oftetraboric acid ester. Where the reaction is highly exothermic, thereaction mixture is preferably cooled during the reaction.

The lubricating greases to which this invention relate are thosecontaining metal soaps of high molecular weight hydroxy fatty acids insufficient proportions to provide at least a substantial thickeningeffect. The metal com- 3,125,523 Patented Mar. 17, 1964 ponent may beany metal which is suitable for forming soaps as thickening agents inlubricating greases generally, including sodium, potassium, lithium,calcium, barium, strontium, aluminum, magnesium, zinc, etc. The alkalimetals and alkaline earth metals comprise a preferred class of metalsfor this purpose. The hydroxy fatty acid soap will usually be present inthe composition in amounts from about 3 to about 15 percent by weight,although somewhat smaller or larger amounts are also suitable, such asamounts as low as about 2 percent by weight and as high as about 30percent by Weight of the composition.

The diboro acid-amine salts are ordinarily employed in these lubricatinggreases in amounts in about the range 0.1-1O percent by weight, althoughsomewhat larger or smaller amounts may be employed if desired. They aremost suitably employed in amounts in about the range 0.5-5 percent byweight of the grease composition.

Suitable soap forming acid materials which may be employed in theproduction of these greases include hydroxy fatty acids containing fromabout '12 to about 24 carbon atoms per molecule and one or more hydroxygroups separated from the carboxylic group by at least one carbon atom,and the glycerides and other esters of such acids. The preferred acidsare substantially saturated acids containing from about 16 to about 22carbon atoms and one or two hydroxy groups per molecule. Such materialsmay be obtained from naturally occurring glycerides, by hydroxylation offatty acids, by hydrogenation of ricinoleic acid or castor oil, orotherwise by processes such as the catalytic oxidation of hydrocarbonoils and waxes which have been extracted and fractionated to the desiredmolecular range. Mixtures of hydroxy acids together with unsubstitutedfatty acids may be very suitably employed, wherein the hydroxy fattyacid comprises at least about one third of the fatty acid mixture.

Lubricating oils employed in the greases include conventional mineraloils and synthetic oils, such as high molecular weight ethers, esters,silicones, etc. Suitable mineral oils include both paraffinic andnaphthenic oils and blends thereof, having viscosities in the range fromabout seconds Saybolt Universal at F. to about 225 seconds SayboltUniversal at 210 F. A particularly suitable class of syntheticlubricating oils comprises synthetic dicarboxylic acid esters, such asdi-Z-ethylhexyl sebacate, (di-secondary amyl) sebacate, di-Z-ethylhexylazelate, etc., and polymers obtained by condensing dicarboxylic acidswith glycols as disclosed in US. 2,628,- 974, as well as the sulfuranalogs of such esters. Other synthetic oils which may be employed inaccordance with this invention include the silicone polymers, includingdialkyl silicone polymers such as dimethyl silicone polymer, diethylsilicone polymer, and mixed aryl-alkyl silicone polymers such as phenylmethyl silicone polymer, having viscosities in the lubricating oilviscosity range.

The grease preparation may be carried out in any suitable manner. Thediboro acid-amine salt may be added either during the grease preparationor it may be incorporated into the preformed grease by heating a mixtureof the grease and diboro acid-amine salt at a mod erately elevatedtemperature with stirring, preferably followed by milling. lt isconveniently added during the grease preparation when the mixture hascooled to about 200 F.

The lubricating greases of this invention may also contain otheradditives of various types such as are commonly employed in lubricatinggreases, such as extreme pressure agents, anti-corrosives,anti-oxidants, etc., as well as other thickening agents, such as finelydivided solids having grease forming properties.

The following example is given for the purpose of further disclosing theinvention.

EXAMPLE I A lubricating grease representing a preferred embodiment ofthis invention having the following composition in percent by Weight:

Lithium 12-hydroxystearate 7.1 Amine salt of diboro acid 3.0 Lubricatingoil Remainder The lubricating oil is a mixture in a 3:1 ratio by weightrespectively of Z-ethylhexyl sebacate and a refined paraffinicdistillate oil having a Saybolt Universal viscosity of about 100 secondsat 100 F.

The amine salts of diboro acids are prepared as described in the saidcopending application. For example, the amine salt ofpenta(nonylphenoxy) diboro acid is obtained in the following manner: 110grams of nonylphenol (0.5 mol) is added to 459 grams oftetra-nonylphenoxy) diborate (0.5 mol). Adduct or complex formation isindicated by an increase in temperature of the mixture from 27 C. to 35C. Thereafter, 100 grams of tertiary alkyl (C -C primary amine (0.5 mol)is added to the mixture, this amine being a commercial product soldunder the trade name of Prirnene 81-R. A further temperature increasefrom C. to C. is observed. The product is distilled to remove thesolvent, and tertiary alkyl (C -C primary amine-penta(nonylphenoxy)diborate is obtained.

The grease preparation is carried out by saponifying Hydrofol acids 200with a small excess of lithium hydroxide in the presence of a majorproportion of the mineral oil contained in the grease, and thereafterblending in the ester oil. The saponification is accomplished by heatingthe mixture for 1 /2 hours at about 317 F. The saponification mixture isthen heated up to 400 F. while adding Z-ethylhexyl sebacate andcirculating the mixture through a shear valve at pounds pressure dropWhile the temperature is maintained at 400 F. The mixture is then cooledto 200 F. during about 2 /2 hours while additional amounts of mineraloil and 2-ethylhexyl sebacate are added. The grease is finally drawn andfinished by milling in a Premier colloid mill. Diboro acid-amine salt isincorporated into the base grease thus obtained by heating a mixture ofthe grease and the amine salt in suitable proportions by weight at F.for 30 minutes with stirring, and then milling with one pass through aPremier colloid mill at 0.002 inch clearance.

The following table shows the effect of the diboro acid-amine salt uponthe dropping point of a grease obtained as described above.

Table I Dropping point, Diboro acid-amine salt: ASTM, F.

None 366 Amine salt of penta(nonylphenoxy) diboro acid 491 In additionto the increased dropping points obtained with diboro acid-amine salts,these compounds also produce large improvements in the Water absorptionproperties of hydroxy fatty acid soap thickened greases which normallyundergo objectionable penetration changes due to water absorption.

Obviously many modifications and variations of the invention, ashereinbefore set forth, may be made without departing from the spiritand scope thereof and only such limitations should be imposed as areindicated in the appended claims.

We claim:

1. A lubricating grease consisting essentially of a lubricating oilthickened to a grease consistency by a metal hydroxy fatty acid soap andcontaining about 0.1-10 percent by weight of the class of amine salts ofdiboro acids represented by the formula:

RRRNIHBOT3(OR)1 03 wherein R is a hydrocarbyl radical containing 1-24carbon atoms, R is selected from the class consisting of aliphatichydrocarbyl and hydroxy substituted aliphatic hydrocarbyl radicalscontaining 1-30 carbon atoms, and R" and R are selected from the classconsisting of hydrogen, aliphatic hydrocarbyl and hydroxy substitutedaliphatic hydrocarbyl radicals containg 1-24 carbon atoms.

2. A lubricating grease according to claim 1 wherein R is a tertiaryaliphatic hydrocarbyl group containing 8-24 carbon atoms and R" and Rare hydrogen.

3. A lubricating grease according to claim 1 wherein the said hydroxyfatty acid soap is a lithium soap.

4. A lubricating grease according to claim 1 wherein the said amine saltof diboro acid is a tertiary alkyl (C -C primary amine salt ofpenta(nonylphenoxy) diboro acid.

5. A lubricating grease according to claim 1 wherein the saidlubricating oil is a mineral oil.

6. A lubricating grease according to claim 1 wherein the saidlubricating oil is a dicarboxylic acid ester.

References Cited in the file of this patent UNITED STATES PATENTS2,846,394 Brunstrum et a1. Aug. 5, 1958 2,961,443 Ashby et al Nov. 22,1960

1. A LUBRICATING GREASE CONSISTING ESSENTIALLY OF A LUBRICATING OILTHICKENED TO A GREASE CONSISTENCY BY A METAL HYDROXY FATTY ACID SOAP ANDCONTAINING ABOUT 0.1-10 PERCENT BY WEIGHT OF THE CLASS OF AMINE SALTS OFDIBORO ACIDS REPRESENTED BY THE FORMULA: